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Adolescent Interpersonal Behaviours and Mental Health Across Two Swedish Cohorts: 15-Year Trends and One-Year Bidirectional Associations in a Mixed-Methods Study

Nilsson, Moa LU orcid ; Claréus, Benjamin LU ; Bjärehed, Jonas LU ; Bjärehed, Marlene LU and Daukantaité, Daiva LU (2025) In Child and Adolescent Psychiatry and Mental Health 19(61).
Abstract
Background and Aims
Adolescent mental health has declined in recent decades. Few studies have explored whether shifts in interpersonal behaviours– both in-person and online– can help explain this decline. Using data from two Swedish cohorts (2007–2008, 2023–2024), we examined (1) 15-year time trends (2007–2008 vs. 2023–2024) in interpersonal behaviours (victimization, aggression, prosocial behaviours) and mental health (externalizing/internalizing problems); (2) one-year bidirectional associations between them; (3) the unique role of cybervictimization/cyberaggression in relation to mental health; and (4) adolescents’ accounts of online experiences that made them ‘feel bad’.

Methods
Two longitudinal school cohorts of... (More)
Background and Aims
Adolescent mental health has declined in recent decades. Few studies have explored whether shifts in interpersonal behaviours– both in-person and online– can help explain this decline. Using data from two Swedish cohorts (2007–2008, 2023–2024), we examined (1) 15-year time trends (2007–2008 vs. 2023–2024) in interpersonal behaviours (victimization, aggression, prosocial behaviours) and mental health (externalizing/internalizing problems); (2) one-year bidirectional associations between them; (3) the unique role of cybervictimization/cyberaggression in relation to mental health; and (4) adolescents’ accounts of online experiences that made them ‘feel bad’.

Methods
Two longitudinal school cohorts of Swedish adolescents (2007–2008: N = 911–987, Mage = 13.71–14.76 years; 2023–2024: N = 768–806, Mage = 13.89–14.89 years) completed self-report measures of interpersonal behaviours and mental health. In 2023–2024, a subset of adolescents (n = 127, 16.5%) answered open-ended questions about negative online experiences.

Results
From 2007 to 2008 to 2023–2024, prosocial behaviours moderately declined for girls and boys, while internalizing problems increased moderately for girls and weakly for boys. Meanwhile, victimization, aggression, and externalizing problems increased at a weak-to-moderate level among girls. Victimization and being treated well by others showed moderate bidirectional relationships with mental health. Cybervictimization/cyberaggression had weaker associations with mental health than did in-person behaviours. According to the qualitative analysis of negative online experiences, adolescents reported harassment, social exclusion, perceived standards/expectations, time-consuming activities, and exposure to distressing content.

Conclusions
Deteriorating adolescent mental health over the past 15 years has occurred alongside rising interpersonal difficulties. The findings further suggest a reciprocal relationship between social challenges and mental health, with hostile online environments amplifying– but not primarily driving– these issues. A holistic perspective that accounts for both in-person and online experiences is essential to better understand and support adolescent well-being. (Less)
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author
; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Child and Adolescent Psychiatry and Mental Health
volume
19
issue
61
publisher
BioMed Central (BMC)
external identifiers
  • pmid:40399919
ISSN
1753-2000
DOI
10.1186/s13034-025-00913-5
language
English
LU publication?
yes
id
15831538-4e32-422a-9fc7-12c064be6997
date added to LUP
2025-05-22 09:05:19
date last changed
2025-05-23 03:33:51
@article{15831538-4e32-422a-9fc7-12c064be6997,
  abstract     = {{Background and Aims<br/>Adolescent mental health has declined in recent decades. Few studies have explored whether shifts in interpersonal behaviours– both in-person and online– can help explain this decline. Using data from two Swedish cohorts (2007–2008, 2023–2024), we examined (1) 15-year time trends (2007–2008 vs. 2023–2024) in interpersonal behaviours (victimization, aggression, prosocial behaviours) and mental health (externalizing/internalizing problems); (2) one-year bidirectional associations between them; (3) the unique role of cybervictimization/cyberaggression in relation to mental health; and (4) adolescents’ accounts of online experiences that made them ‘feel bad’.<br/><br/>Methods<br/>Two longitudinal school cohorts of Swedish adolescents (2007–2008: N = 911–987, Mage = 13.71–14.76 years; 2023–2024: N = 768–806, Mage = 13.89–14.89 years) completed self-report measures of interpersonal behaviours and mental health. In 2023–2024, a subset of adolescents (n = 127, 16.5%) answered open-ended questions about negative online experiences.<br/><br/>Results<br/>From 2007 to 2008 to 2023–2024, prosocial behaviours moderately declined for girls and boys, while internalizing problems increased moderately for girls and weakly for boys. Meanwhile, victimization, aggression, and externalizing problems increased at a weak-to-moderate level among girls. Victimization and being treated well by others showed moderate bidirectional relationships with mental health. Cybervictimization/cyberaggression had weaker associations with mental health than did in-person behaviours. According to the qualitative analysis of negative online experiences, adolescents reported harassment, social exclusion, perceived standards/expectations, time-consuming activities, and exposure to distressing content.<br/><br/>Conclusions<br/>Deteriorating adolescent mental health over the past 15 years has occurred alongside rising interpersonal difficulties. The findings further suggest a reciprocal relationship between social challenges and mental health, with hostile online environments amplifying– but not primarily driving– these issues. A holistic perspective that accounts for both in-person and online experiences is essential to better understand and support adolescent well-being.}},
  author       = {{Nilsson, Moa and Claréus, Benjamin and Bjärehed, Jonas and Bjärehed, Marlene and Daukantaité, Daiva}},
  issn         = {{1753-2000}},
  language     = {{eng}},
  month        = {{05}},
  number       = {{61}},
  publisher    = {{BioMed Central (BMC)}},
  series       = {{Child and Adolescent Psychiatry and Mental Health}},
  title        = {{Adolescent Interpersonal Behaviours and Mental Health Across Two Swedish Cohorts: 15-Year Trends and One-Year Bidirectional Associations in a Mixed-Methods Study}},
  url          = {{http://dx.doi.org/10.1186/s13034-025-00913-5}},
  doi          = {{10.1186/s13034-025-00913-5}},
  volume       = {{19}},
  year         = {{2025}},
}